No abstract

Background: Brackets' debonding without any damage to the teeth is very important. Objectives: The aim of this study was to compare the debonding characteristics of the metal conventional and self-ligating brackets. Patients and Methods: 69 maxillary premolars were randomly assigned in 3 groups. Metal brackets of Damon, In Ovation and conventional systems were bonded to the teeth. The brackets were debonded with debonding pliers. Debonding strengths, adhesive remnant index, and enamel damage were evaluated. A Zwick model universal testing machine was used to measure debonding strengths. The debonding strength values were statistically analyzed by one-sided analysis of variance while the increase in the enamel crack numbers and length and the remained adhesive index were analyzed by chi-square test. Results: The means of the debonding strength in the brackets of in ovation, damon and conventional systems were 15.22, 11.4 and 8.67 MPa respectively. Significant differences were observed regarding debonding strength between three types of brackets (all: P < 0.001). After debonding of in ovation, damon and stainless steel brackets; the increased numbers of the enamel cracks were noted in 26.06%, 21.74% and 17.39% cases respectively. Also, the increased cracks lengths were demonstrated in 47.83%, 39.13%, and 30.43% cases. No significant differences were observed regarding the increase of the enamel cracks number and length and the amounts of residual adhesive on the teeth. Conclusions: The debonding characteristics of the metal self-ligating were comparable to the conventional brackets.

The current study aimed to investigate the effect of biocompatible kinds of toothpastes containing natural ingredients such as theobromine and caffeine on the enamel microhardness after demineralization. 72 maxillary premolar teeth extracted for orthodontic purposes were used in this study. Primary enamel surface microhardness examinations were performed using a Digital Micro Vickers Hardness Tester following the Knoop technique (50 g load for 15 s with three indentations at various points). The specimens were immersed in lactic acid (pH = 5.4) for 7 days, washed with distilled water, dried, and then retested for microhardness. According to the type of toothpaste used for brushing, all specimens were categorized as follows: Group 1, Theodent classic® toothpaste (theobromine); Group 2, Power Energy toothpaste (caffeine); Group 3, Colgate toothpaste (fluoride); and Group 4, distilled water as the negative control. The specimens were retested for enamel microhardness after brushing 2 times a day for one month. After brushing with different types of toothpaste, for all experiment groups, the increase in microhardness values in the demineralized enamel surfaces was significant and there were significant differences between them ( p value <0.05). The fluoride group had the highest microhardness and had a significant difference with the caffeine and distilled water groups, but there was no significant difference with the theobromine group ( p value <0.05). In the theobromine group, the hardness was considerably higher than in the caffeine and distilled water groups. There was no significant difference between the caffeine and distilled water groups. Theobromine toothpaste had the same remineralization effect as that of fluoride toothpaste, while caffeine toothpaste had no positive effect on the remineralization process.

The present study, intended to compare the effects of immersion in herbal mouthwashes and the Chlorhexidine mouthwash on orthodontic acrylic resin, specifically with regard to alterations in its hardness, roughness and color. Seventy-two specimens of Orthodontic self-cured acrylic resin were used for the experiments. After preparation, specimens were placed in three types of mouthwash including Chlorhexidine 0.2 % (CHX), Persica and Matrica. The changes in microhardness (ΔKNH), Surface roughness (ΔRa) and color (ΔE) were evaluated prior to and following the immersion in mouthwashes. In order to analyze the data, we made use of SPSS version 22. One-Way ANOVA test was used to find the differences between groups. The Tukey test was conducted in the final stage. It was revealed that acrylic resins had lower microhardness when 12 hours after immersion had taken place. There were significant differences after 12h, 24h and 7 days between the groups in the softening of acrylic resins. The reduction in microhardness of acrylic resin with herbal mouthwashes in the three-time intervals was higher than CHX. With regard to increasing surface roughness, the disparity between herbal mouthwashes was insignificant. However herbal mouthwashes significantly increased the value of roughness more than CHX. Changes in color were significantly higher in all mouthwashes. Herbal mouthwashes caused more color variation than CHX. The color, roughness and hardness of acrylic resin undergo changes as a result of being immersed in the mouthwashes. However, the effect of herbal mouthwashes was more than that of CHX.

No abstract

Aim:The aim of this study was to compare dentoskeletal effects and patient's satisfaction with a modified twin-block (clear twinblock) and classic twin-block. Materials and methods:A total of 62 patients with skeletal class II malocclusion contributing to mandibular retrognathism with a minimum of 4 mm overjet, the FMA angle between 20 to 25 degree and being in stage 2 to 3 of cervical vertebral maturation participated in this study. Subjects were randomized in 1:1 ratio to classic and clear twin-block. Lateral cephalograms were taken at two stages-Pre-and post-treatment (when the overjet reduced to 1 to 0 mm). All the measurements were done with Dolphin software version 10.5. Four months after the start of the treatment the patients were asked to fill the questioners regarding their compliance from the appliances.Results: Both classic and clear twin -block groups showed mandibular advancement without statistically significant difference between them. However, SNB angle increased slightly more in clear group than the classic one.'' Headgear effect'' is not statistically noticeable in both groups. However, SNA angle decreased slightly more in Classic group. Increased in lower incisors proclination was happening in both groups, but in a clear group, this increase was significantly less. Overbite reduction could be seen in both groups with significantly more reduction in the classic group. Conclusion:Increase in lower incisors proclination was less in clear group than the classic one. Overbite reduction was more in the classic group than the classic one.Clinical significance: Clear twin-block is more beneficial in skeletal class II patients with proclined lower incisors and vertical growth pattern.

Aim. The aim of this study was to compare lower dental arch changes using two types of space regainers, including a removable appliance with a distalizing screw and a fixed double-banded appliance. Methods and Materials. In this case-control study, the study sample was comprised of thirty-eight children with mixed dentitions, all of whom had unilateral space deficiency due to premature loss of the second deciduous molar in the mandibular arch. Patients were treated with either a removable appliance with a distalizing screw or a fixed double-banded space regainer (DBSR) (n = 19). Pre- and posttreatment dental casts and lateral cephalograms of patients were evaluated to compare the effects of the two space-regaining devices on the mandibular dental arch. The data were analyzed using paired and independent t-tests. Results. Available space, molar angle, IMPA, and the first molar distance to the mandibular plane and symphysis increased significantly in both groups ( P < 0.001 ). The mean amount of IMPA changes was significantly greater in the distalizing screw group than in the DBSR group ( P < 0.05 ). But, there were no statistically significant differences between the mean changes of available space, molar angle, and the first molar distance to the mandibular plane and symphysis in the distalizing screw and the DBSR group ( P < 0.05 ). The DBSR group’s treatment time was significantly shorter ( P < 0.001 ). Conclusion. The removable device with a distalizing screw and the DBSR were both able to regain mild-to-moderate unilateral space loss, achieving an increase in molar angle, IMPA, and molar extrusion. However, treatment time with the DBSR was shorter and with less incisor tipping as a side effect.

No abstract